在Python3中，当我读取二进制文件时，为什么'b'会放在内容之前？

Question

For example I'm trying to read a file as follows

fd = open('mydb.dbf', 'rb')
print(fd.read(1))

The output is:

b'\\x03'

I wish for only '\\x03'. Where is the extra character coming from?

Answer 1

There is no extra character. You have a bytes object, whose contents are the single byte \\x03 .

The print function prints the str representation of any object. A bytes object prints out as b'\\x03' . But that b is no more part of the value than the quotes are (or, for that matter, the backslash, x, or two digits).

To convince yourself of this fact, try print(len(my_bytes)) or print(my_bytes[0]) . The length is 1 ; the first value is the (byte) number 3 .

(If you didn't want a bytes object, you shouldn't have opened the file in binary mode. But, considering that the first character is a control-C, you probably did want a bytes object.)